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676 lines
25 KiB
676 lines
25 KiB
5 years ago
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# Copyright (c) 2009-2011 Denis Bilenko. See LICENSE for details.
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"""
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Managing greenlets in a group.
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The :class:`Group` class in this module abstracts a group of running
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greenlets. When a greenlet dies, it's automatically removed from the
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group. All running greenlets in a group can be waited on with
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:meth:`Group.join`, or all running greenlets can be killed with
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:meth:`Group.kill`.
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The :class:`Pool` class, which is a subclass of :class:`Group`,
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provides a way to limit concurrency: its :meth:`spawn <Pool.spawn>`
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method blocks if the number of greenlets in the pool has already
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reached the limit, until there is a free slot.
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"""
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from __future__ import print_function, absolute_import, division
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from gevent.hub import GreenletExit, getcurrent, kill as _kill
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from gevent.greenlet import joinall, Greenlet
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from gevent.queue import Full as QueueFull
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from gevent.timeout import Timeout
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from gevent.event import Event
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from gevent.lock import Semaphore, DummySemaphore
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from gevent._compat import izip
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from gevent._imap import IMap
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from gevent._imap import IMapUnordered
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__all__ = [
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'Group',
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'Pool',
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'PoolFull',
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]
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class GroupMappingMixin(object):
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# Internal, non-public API class.
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# Provides mixin methods for implementing mapping pools. Subclasses must define:
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def spawn(self, func, *args, **kwargs):
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"""
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A function that runs *func* with *args* and *kwargs*, potentially
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asynchronously. Return a value with a ``get`` method that blocks
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until the results of func are available, and a ``rawlink`` method
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that calls a callback when the results are available.
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If this object has an upper bound on how many asyncronously executing
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tasks can exist, this method may block until a slot becomes available.
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"""
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raise NotImplementedError()
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def _apply_immediately(self):
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"""
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should the function passed to apply be called immediately,
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synchronously?
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"""
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raise NotImplementedError()
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def _apply_async_use_greenlet(self):
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"""
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Should apply_async directly call Greenlet.spawn(), bypassing
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`spawn`?
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Return true when self.spawn would block.
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"""
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raise NotImplementedError()
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def _apply_async_cb_spawn(self, callback, result):
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"""
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Run the given callback function, possibly
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asynchronously, possibly synchronously.
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"""
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raise NotImplementedError()
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def apply_cb(self, func, args=None, kwds=None, callback=None):
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"""
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:meth:`apply` the given *func(\\*args, \\*\\*kwds)*, and, if a *callback* is given, run it with the
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results of *func* (unless an exception was raised.)
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The *callback* may be called synchronously or asynchronously. If called
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asynchronously, it will not be tracked by this group. (:class:`Group` and :class:`Pool`
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call it asynchronously in a new greenlet; :class:`~gevent.threadpool.ThreadPool` calls
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it synchronously in the current greenlet.)
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"""
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result = self.apply(func, args, kwds)
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if callback is not None:
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self._apply_async_cb_spawn(callback, result)
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return result
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def apply_async(self, func, args=None, kwds=None, callback=None):
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"""
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A variant of the :meth:`apply` method which returns a :class:`~.Greenlet` object.
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When the returned greenlet gets to run, it *will* call :meth:`apply`,
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passing in *func*, *args* and *kwds*.
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If *callback* is specified, then it should be a callable which
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accepts a single argument. When the result becomes ready
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callback is applied to it (unless the call failed).
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This method will never block, even if this group is full (that is,
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even if :meth:`spawn` would block, this method will not).
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.. caution:: The returned greenlet may or may not be tracked
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as part of this group, so :meth:`joining <join>` this group is
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not a reliable way to wait for the results to be available or
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for the returned greenlet to run; instead, join the returned
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greenlet.
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.. tip:: Because :class:`~.ThreadPool` objects do not track greenlets, the returned
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greenlet will never be a part of it. To reduce overhead and improve performance,
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:class:`Group` and :class:`Pool` may choose to track the returned
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greenlet. These are implementation details that may change.
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"""
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if args is None:
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args = ()
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if kwds is None:
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kwds = {}
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if self._apply_async_use_greenlet():
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# cannot call self.spawn() directly because it will block
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# XXX: This is always the case for ThreadPool, but for Group/Pool
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# of greenlets, this is only the case when they are full...hence
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# the weasely language about "may or may not be tracked". Should we make
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# Group/Pool always return true as well so it's never tracked by any
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# implementation? That would simplify that logic, but could increase
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# the total number of greenlets in the system and add a layer of
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# overhead for the simple cases when the pool isn't full.
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return Greenlet.spawn(self.apply_cb, func, args, kwds, callback)
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greenlet = self.spawn(func, *args, **kwds)
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if callback is not None:
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greenlet.link(pass_value(callback))
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return greenlet
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def apply(self, func, args=None, kwds=None):
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"""
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Rough quivalent of the :func:`apply()` builtin function blocking until
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the result is ready and returning it.
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The ``func`` will *usually*, but not *always*, be run in a way
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that allows the current greenlet to switch out (for example,
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in a new greenlet or thread, depending on implementation). But
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if the current greenlet or thread is already one that was
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spawned by this pool, the pool may choose to immediately run
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the `func` synchronously.
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Any exception ``func`` raises will be propagated to the caller of ``apply`` (that is,
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this method will raise the exception that ``func`` raised).
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"""
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if args is None:
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args = ()
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if kwds is None:
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kwds = {}
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if self._apply_immediately():
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return func(*args, **kwds)
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return self.spawn(func, *args, **kwds).get()
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def __map(self, func, iterable):
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return [g.get() for g in
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[self.spawn(func, i) for i in iterable]]
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def map(self, func, iterable):
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"""Return a list made by applying the *func* to each element of
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the iterable.
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.. seealso:: :meth:`imap`
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"""
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# We can't return until they're all done and in order. It
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# wouldn't seem to much matter what order we wait on them in,
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# so the simple, fast (50% faster than imap) solution would be:
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# return [g.get() for g in
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# [self.spawn(func, i) for i in iterable]]
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# If the pool size is unlimited (or more than the len(iterable)), this
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# is equivalent to imap (spawn() will never block, all of them run concurrently,
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# we call get() in the order the iterable was given).
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# Now lets imagine the pool if is limited size. Suppose the
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# func is time.sleep, our pool is limited to 3 threads, and
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# our input is [10, 1, 10, 1, 1] We would start three threads,
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# one to sleep for 10, one to sleep for 1, and the last to
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# sleep for 10. We would block starting the fourth thread. At
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# time 1, we would finish the second thread and start another
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# one for time 1. At time 2, we would finish that one and
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# start the last thread, and then begin executing get() on the first
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# thread.
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# Because it's spawn that blocks, this is *also* equivalent to what
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# imap would do.
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# The one remaining difference is that imap runs in its own
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# greenlet, potentially changing the way the event loop runs.
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# That's easy enough to do.
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g = Greenlet.spawn(self.__map, func, iterable)
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return g.get()
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def map_cb(self, func, iterable, callback=None):
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result = self.map(func, iterable)
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if callback is not None:
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callback(result)
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return result
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def map_async(self, func, iterable, callback=None):
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"""
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A variant of the map() method which returns a Greenlet object that is executing
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the map function.
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If callback is specified then it should be a callable which accepts a
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single argument.
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"""
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return Greenlet.spawn(self.map_cb, func, iterable, callback)
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def __imap(self, cls, func, *iterables, **kwargs):
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# Python 2 doesn't support the syntax that lets us mix varargs and
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# a named kwarg, so we have to unpack manually
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maxsize = kwargs.pop('maxsize', None)
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if kwargs:
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raise TypeError("Unsupported keyword arguments")
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return cls.spawn(func, izip(*iterables), spawn=self.spawn,
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_zipped=True, maxsize=maxsize)
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def imap(self, func, *iterables, **kwargs):
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"""
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imap(func, *iterables, maxsize=None) -> iterable
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An equivalent of :func:`itertools.imap`, operating in parallel.
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The *func* is applied to each element yielded from each
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iterable in *iterables* in turn, collecting the result.
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If this object has a bound on the number of active greenlets it can
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contain (such as :class:`Pool`), then at most that number of tasks will operate
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in parallel.
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:keyword int maxsize: If given and not-None, specifies the maximum number of
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finished results that will be allowed to accumulate awaiting the reader;
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more than that number of results will cause map function greenlets to begin
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to block. This is most useful if there is a great disparity in the speed of
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the mapping code and the consumer and the results consume a great deal of resources.
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.. note:: This is separate from any bound on the number of active parallel
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tasks, though they may have some interaction (for example, limiting the
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number of parallel tasks to the smallest bound).
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.. note:: Using a bound is slightly more computationally expensive than not using a bound.
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.. tip:: The :meth:`imap_unordered` method makes much better
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use of this parameter. Some additional, unspecified,
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number of objects may be required to be kept in memory
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to maintain order by this function.
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:return: An iterable object.
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.. versionchanged:: 1.1b3
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Added the *maxsize* keyword parameter.
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.. versionchanged:: 1.1a1
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Accept multiple *iterables* to iterate in parallel.
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"""
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return self.__imap(IMap, func, *iterables, **kwargs)
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def imap_unordered(self, func, *iterables, **kwargs):
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"""
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imap_unordered(func, *iterables, maxsize=None) -> iterable
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The same as :meth:`imap` except that the ordering of the results
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from the returned iterator should be considered in arbitrary
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order.
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This is lighter weight than :meth:`imap` and should be preferred if order
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doesn't matter.
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.. seealso:: :meth:`imap` for more details.
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"""
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return self.__imap(IMapUnordered, func, *iterables, **kwargs)
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class Group(GroupMappingMixin):
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"""
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Maintain a group of greenlets that are still running, without
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limiting their number.
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Links to each item and removes it upon notification.
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Groups can be iterated to discover what greenlets they are tracking,
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they can be tested to see if they contain a greenlet, and they know the
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number (len) of greenlets they are tracking. If they are not tracking any
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greenlets, they are False in a boolean context.
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.. attribute:: greenlet_class
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Either :class:`gevent.Greenlet` (the default) or a subclass.
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These are the type of
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object we will :meth:`spawn`. This can be
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changed on an instance or in a subclass.
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"""
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greenlet_class = Greenlet
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def __init__(self, *args):
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assert len(args) <= 1, args
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self.greenlets = set(*args)
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if args:
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for greenlet in args[0]:
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greenlet.rawlink(self._discard)
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# each item we kill we place in dying, to avoid killing the same greenlet twice
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self.dying = set()
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self._empty_event = Event()
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self._empty_event.set()
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def __repr__(self):
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return '<%s at 0x%x %s>' % (self.__class__.__name__, id(self), self.greenlets)
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def __len__(self):
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"""
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Answer how many greenlets we are tracking. Note that if we are empty,
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we are False in a boolean context.
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"""
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return len(self.greenlets)
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def __contains__(self, item):
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"""
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Answer if we are tracking the given greenlet.
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"""
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return item in self.greenlets
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def __iter__(self):
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"""
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Iterate across all the greenlets we are tracking, in no particular order.
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"""
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return iter(self.greenlets)
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def add(self, greenlet):
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"""
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Begin tracking the *greenlet*.
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If this group is :meth:`full`, then this method may block
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until it is possible to track the greenlet.
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Typically the *greenlet* should **not** be started when
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it is added because if this object blocks in this method,
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then the *greenlet* may run to completion before it is tracked.
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"""
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try:
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rawlink = greenlet.rawlink
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except AttributeError:
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pass # non-Greenlet greenlet, like MAIN
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else:
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rawlink(self._discard)
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self.greenlets.add(greenlet)
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self._empty_event.clear()
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def _discard(self, greenlet):
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self.greenlets.discard(greenlet)
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self.dying.discard(greenlet)
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if not self.greenlets:
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self._empty_event.set()
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def discard(self, greenlet):
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"""
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Stop tracking the greenlet.
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"""
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self._discard(greenlet)
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try:
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unlink = greenlet.unlink
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|
|
except AttributeError:
|
||
|
|
pass # non-Greenlet greenlet, like MAIN
|
||
|
|
else:
|
||
|
|
unlink(self._discard)
|
||
|
|
|
||
|
|
def start(self, greenlet):
|
||
|
|
"""
|
||
|
|
Add the **unstarted** *greenlet* to the collection of greenlets
|
||
|
|
this group is monitoring, and then start it.
|
||
|
|
"""
|
||
|
|
self.add(greenlet)
|
||
|
|
greenlet.start()
|
||
|
|
|
||
|
|
def spawn(self, *args, **kwargs): # pylint:disable=arguments-differ
|
||
|
|
"""
|
||
|
|
Begin a new greenlet with the given arguments (which are passed
|
||
|
|
to the greenlet constructor) and add it to the collection of greenlets
|
||
|
|
this group is monitoring.
|
||
|
|
|
||
|
|
:return: The newly started greenlet.
|
||
|
|
"""
|
||
|
|
greenlet = self.greenlet_class(*args, **kwargs)
|
||
|
|
self.start(greenlet)
|
||
|
|
return greenlet
|
||
|
|
|
||
|
|
# def close(self):
|
||
|
|
# """Prevents any more tasks from being submitted to the pool"""
|
||
|
|
# self.add = RaiseException("This %s has been closed" % self.__class__.__name__)
|
||
|
|
|
||
|
|
def join(self, timeout=None, raise_error=False):
|
||
|
|
"""
|
||
|
|
Wait for this group to become empty *at least once*.
|
||
|
|
|
||
|
|
If there are no greenlets in the group, returns immediately.
|
||
|
|
|
||
|
|
.. note:: By the time the waiting code (the caller of this
|
||
|
|
method) regains control, a greenlet may have been added to
|
||
|
|
this group, and so this object may no longer be empty. (That
|
||
|
|
is, ``group.join(); assert len(group) == 0`` is not
|
||
|
|
guaranteed to hold.) This method only guarantees that the group
|
||
|
|
reached a ``len`` of 0 at some point.
|
||
|
|
|
||
|
|
:keyword bool raise_error: If True (*not* the default), if any
|
||
|
|
greenlet that finished while the join was in progress raised
|
||
|
|
an exception, that exception will be raised to the caller of
|
||
|
|
this method. If multiple greenlets raised exceptions, which
|
||
|
|
one gets re-raised is not determined. Only greenlets currently
|
||
|
|
in the group when this method is called are guaranteed to
|
||
|
|
be checked for exceptions.
|
||
|
|
|
||
|
|
:return bool: A value indicating whether this group became empty.
|
||
|
|
If the timeout is specified and the group did not become empty
|
||
|
|
during that timeout, then this will be a false value. Otherwise
|
||
|
|
it will be a true value.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.2a1
|
||
|
|
Add the return value.
|
||
|
|
"""
|
||
|
|
greenlets = list(self.greenlets) if raise_error else ()
|
||
|
|
result = self._empty_event.wait(timeout=timeout)
|
||
|
|
|
||
|
|
for greenlet in greenlets:
|
||
|
|
if greenlet.exception is not None:
|
||
|
|
if hasattr(greenlet, '_raise_exception'):
|
||
|
|
greenlet._raise_exception()
|
||
|
|
raise greenlet.exception
|
||
|
|
|
||
|
|
return result
|
||
|
|
|
||
|
|
def kill(self, exception=GreenletExit, block=True, timeout=None):
|
||
|
|
"""
|
||
|
|
Kill all greenlets being tracked by this group.
|
||
|
|
"""
|
||
|
|
timer = Timeout._start_new_or_dummy(timeout)
|
||
|
|
try:
|
||
|
|
while self.greenlets:
|
||
|
|
for greenlet in list(self.greenlets):
|
||
|
|
if greenlet in self.dying:
|
||
|
|
continue
|
||
|
|
try:
|
||
|
|
kill = greenlet.kill
|
||
|
|
except AttributeError:
|
||
|
|
_kill(greenlet, exception)
|
||
|
|
else:
|
||
|
|
kill(exception, block=False)
|
||
|
|
self.dying.add(greenlet)
|
||
|
|
if not block:
|
||
|
|
break
|
||
|
|
joinall(self.greenlets)
|
||
|
|
except Timeout as ex:
|
||
|
|
if ex is not timer:
|
||
|
|
raise
|
||
|
|
finally:
|
||
|
|
timer.cancel()
|
||
|
|
|
||
|
|
def killone(self, greenlet, exception=GreenletExit, block=True, timeout=None):
|
||
|
|
"""
|
||
|
|
If the given *greenlet* is running and being tracked by this group,
|
||
|
|
kill it.
|
||
|
|
"""
|
||
|
|
if greenlet not in self.dying and greenlet in self.greenlets:
|
||
|
|
greenlet.kill(exception, block=False)
|
||
|
|
self.dying.add(greenlet)
|
||
|
|
if block:
|
||
|
|
greenlet.join(timeout)
|
||
|
|
|
||
|
|
def full(self):
|
||
|
|
"""
|
||
|
|
Return a value indicating whether this group can track more greenlets.
|
||
|
|
|
||
|
|
In this implementation, because there are no limits on the number of
|
||
|
|
tracked greenlets, this will always return a ``False`` value.
|
||
|
|
"""
|
||
|
|
return False
|
||
|
|
|
||
|
|
def wait_available(self, timeout=None):
|
||
|
|
"""
|
||
|
|
Block until it is possible to :meth:`spawn` a new greenlet.
|
||
|
|
|
||
|
|
In this implementation, because there are no limits on the number
|
||
|
|
of tracked greenlets, this will always return immediately.
|
||
|
|
"""
|
||
|
|
|
||
|
|
# MappingMixin methods
|
||
|
|
|
||
|
|
def _apply_immediately(self):
|
||
|
|
# If apply() is called from one of our own
|
||
|
|
# worker greenlets, don't spawn a new one---if we're full, that
|
||
|
|
# could deadlock.
|
||
|
|
return getcurrent() in self
|
||
|
|
|
||
|
|
def _apply_async_cb_spawn(self, callback, result):
|
||
|
|
Greenlet.spawn(callback, result)
|
||
|
|
|
||
|
|
def _apply_async_use_greenlet(self):
|
||
|
|
# cannot call self.spawn() because it will block, so
|
||
|
|
# use a fresh, untracked greenlet that when run will
|
||
|
|
# (indirectly) call self.spawn() for us.
|
||
|
|
return self.full()
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
class PoolFull(QueueFull):
|
||
|
|
"""
|
||
|
|
Raised when a Pool is full and an attempt was made to
|
||
|
|
add a new greenlet to it in non-blocking mode.
|
||
|
|
"""
|
||
|
|
|
||
|
|
|
||
|
|
class Pool(Group):
|
||
|
|
|
||
|
|
def __init__(self, size=None, greenlet_class=None):
|
||
|
|
"""
|
||
|
|
Create a new pool.
|
||
|
|
|
||
|
|
A pool is like a group, but the maximum number of members
|
||
|
|
is governed by the *size* parameter.
|
||
|
|
|
||
|
|
:keyword int size: If given, this non-negative integer is the
|
||
|
|
maximum count of active greenlets that will be allowed in
|
||
|
|
this pool. A few values have special significance:
|
||
|
|
|
||
|
|
* `None` (the default) places no limit on the number of
|
||
|
|
greenlets. This is useful when you want to track, but not limit,
|
||
|
|
greenlets. In general, a :class:`Group`
|
||
|
|
may be a more efficient way to achieve the same effect, but some things
|
||
|
|
need the additional abilities of this class (one example being the *spawn*
|
||
|
|
parameter of :class:`gevent.baseserver.BaseServer` and
|
||
|
|
its subclass :class:`gevent.pywsgi.WSGIServer`).
|
||
|
|
|
||
|
|
* ``0`` creates a pool that can never have any active greenlets. Attempting
|
||
|
|
to spawn in this pool will block forever. This is only useful
|
||
|
|
if an application uses :meth:`wait_available` with a timeout and checks
|
||
|
|
:meth:`free_count` before attempting to spawn.
|
||
|
|
"""
|
||
|
|
if size is not None and size < 0:
|
||
|
|
raise ValueError('size must not be negative: %r' % (size, ))
|
||
|
|
Group.__init__(self)
|
||
|
|
self.size = size
|
||
|
|
if greenlet_class is not None:
|
||
|
|
self.greenlet_class = greenlet_class
|
||
|
|
if size is None:
|
||
|
|
factory = DummySemaphore
|
||
|
|
else:
|
||
|
|
factory = Semaphore
|
||
|
|
self._semaphore = factory(size)
|
||
|
|
|
||
|
|
def wait_available(self, timeout=None):
|
||
|
|
"""
|
||
|
|
Wait until it's possible to spawn a greenlet in this pool.
|
||
|
|
|
||
|
|
:param float timeout: If given, only wait the specified number
|
||
|
|
of seconds.
|
||
|
|
|
||
|
|
.. warning:: If the pool was initialized with a size of 0, this
|
||
|
|
method will block forever unless a timeout is given.
|
||
|
|
|
||
|
|
:return: A number indicating how many new greenlets can be put into
|
||
|
|
the pool without blocking.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.1a3
|
||
|
|
Added the ``timeout`` parameter.
|
||
|
|
"""
|
||
|
|
return self._semaphore.wait(timeout=timeout)
|
||
|
|
|
||
|
|
def full(self):
|
||
|
|
"""
|
||
|
|
Return a boolean indicating whether this pool is full, e.g. if
|
||
|
|
:meth:`add` would block.
|
||
|
|
|
||
|
|
:return: False if there is room for new members, True if there isn't.
|
||
|
|
"""
|
||
|
|
return self.free_count() <= 0
|
||
|
|
|
||
|
|
def free_count(self):
|
||
|
|
"""
|
||
|
|
Return a number indicating *approximately* how many more members
|
||
|
|
can be added to this pool.
|
||
|
|
"""
|
||
|
|
if self.size is None:
|
||
|
|
return 1
|
||
|
|
return max(0, self.size - len(self))
|
||
|
|
|
||
|
|
def start(self, greenlet, *args, **kwargs): # pylint:disable=arguments-differ
|
||
|
|
"""
|
||
|
|
start(greenlet, blocking=True, timeout=None) -> None
|
||
|
|
|
||
|
|
Add the **unstarted** *greenlet* to the collection of greenlets
|
||
|
|
this group is monitoring and then start it.
|
||
|
|
|
||
|
|
Parameters are as for :meth:`add`.
|
||
|
|
"""
|
||
|
|
self.add(greenlet, *args, **kwargs)
|
||
|
|
greenlet.start()
|
||
|
|
|
||
|
|
def add(self, greenlet, blocking=True, timeout=None): # pylint:disable=arguments-differ
|
||
|
|
"""
|
||
|
|
Begin tracking the given **unstarted** greenlet, possibly blocking
|
||
|
|
until space is available.
|
||
|
|
|
||
|
|
Usually you should call :meth:`start` to track and start the greenlet
|
||
|
|
instead of using this lower-level method, or :meth:`spawn` to
|
||
|
|
also create the greenlet.
|
||
|
|
|
||
|
|
:keyword bool blocking: If True (the default), this function
|
||
|
|
will block until the pool has space or a timeout occurs. If
|
||
|
|
False, this function will immediately raise a Timeout if the
|
||
|
|
pool is currently full.
|
||
|
|
:keyword float timeout: The maximum number of seconds this
|
||
|
|
method will block, if ``blocking`` is True. (Ignored if
|
||
|
|
``blocking`` is False.)
|
||
|
|
:raises PoolFull: if either ``blocking`` is False and the pool
|
||
|
|
was full, or if ``blocking`` is True and ``timeout`` was
|
||
|
|
exceeded.
|
||
|
|
|
||
|
|
.. caution:: If the *greenlet* has already been started and
|
||
|
|
*blocking* is true, then the greenlet may run to completion
|
||
|
|
while the current greenlet blocks waiting to track it. This would
|
||
|
|
enable higher concurrency than desired.
|
||
|
|
|
||
|
|
.. seealso:: :meth:`Group.add`
|
||
|
|
|
||
|
|
.. versionchanged:: 1.3.0 Added the ``blocking`` and
|
||
|
|
``timeout`` parameters.
|
||
|
|
"""
|
||
|
|
if not self._semaphore.acquire(blocking=blocking, timeout=timeout):
|
||
|
|
# We failed to acquire the semaphore.
|
||
|
|
# If blocking was True, then there was a timeout. If blocking was
|
||
|
|
# False, then there was no capacity. Either way, raise PoolFull.
|
||
|
|
raise PoolFull()
|
||
|
|
|
||
|
|
try:
|
||
|
|
Group.add(self, greenlet)
|
||
|
|
except:
|
||
|
|
self._semaphore.release()
|
||
|
|
raise
|
||
|
|
|
||
|
|
def _discard(self, greenlet):
|
||
|
|
Group._discard(self, greenlet)
|
||
|
|
self._semaphore.release()
|
||
|
|
|
||
|
|
|
||
|
|
class pass_value(object):
|
||
|
|
__slots__ = ['callback']
|
||
|
|
|
||
|
|
def __init__(self, callback):
|
||
|
|
self.callback = callback
|
||
|
|
|
||
|
|
def __call__(self, source):
|
||
|
|
if source.successful():
|
||
|
|
self.callback(source.value)
|
||
|
|
|
||
|
|
def __hash__(self):
|
||
|
|
return hash(self.callback)
|
||
|
|
|
||
|
|
def __eq__(self, other):
|
||
|
|
return self.callback == getattr(other, 'callback', other)
|
||
|
|
|
||
|
|
def __str__(self):
|
||
|
|
return str(self.callback)
|
||
|
|
|
||
|
|
def __repr__(self):
|
||
|
|
return repr(self.callback)
|
||
|
|
|
||
|
|
def __getattr__(self, item):
|
||
|
|
assert item != 'callback'
|
||
|
|
return getattr(self.callback, item)
|